I. Field of the Invention
This invention pertains to the art of rubber-processing additives, and more particularly, to the use of rubber grind in rubber formulations.
II. Description of the Related Art
It has been seen throughout the development and use of rubber and elastomers, that scrap rubber goods are a huge source of environmental hazard. So, for many years, the rubber industry has been concerned with the disposal of scrap rubber. Many attempts have been made to find ways to recycle the scrap rubber, or to destroy it. Many of the past methods have simply burned the scrap rubber or stacked it in huge piles in a large dumping site. The industry has been trying to find ways to cut down on the pollution caused by scrap rubber.
The use of scrap rubber in the production of new rubber is known in the art. The scrap rubber is generally processed so that is becomes a powder, known as rubber grind. The rubber grind is added to the virgin rubber to recycle the rubber grind. The industry has made several bridging compounds that allow the rubber grind to be substituted for virgin rubber, in concentrations of 1-20%. The problem with this is the compounds only allow use of 20% of the rubber grind, and the physical properties of the rubber are lowered. The scorch time and cure time can be affected by as much as 73%.
One known process is disclosed in U.S. Pat. No. 5,303,661 to Yu et al. Yu et al disclose a dry process for treatment of used rubber waste that is refined to get recycled material. The Yu patent discloses the use of zeolite, 1-10% by weight, which is used as a catalyst, causing the process oil to penetrate the rubber waste. One drawback of the Yu patent is it can only use 30% of the rubber waste. The Yu patent does not create a chemical reaction with the zeolite, and therefore the resultant rubber compound is not as strong as the rubber compound formed as a result of the present invention.
Known methods of recycling rubber grind require the use of a desulphurizing agent, pine tar, and calcium carbonate. This mixture is blended and heated for approximately 6-13 hours to obtain the recycled rubber. The mixture is heated at high temperatures that break off the sulfur, creating an oil. The oil is then turned back into the rubber polymer. The drawback of this process is the time involved and the high level of air pollution created by the compound. The gas given off during this process is also toxic.
The present invention contemplates a new and improved rubber-processing additive. Thus, this invention is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results.